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Monday 6 July

Chemical Physics

EOM-CC Excited-State Gradients and Nonadiabatic Couplings on a Consumer GPU from a Contraction-DAG with Laplace-Transform J/K Kernels

Rubén Darío Guerrero

We present a unified, memory-bounded GPU realization of equation-of-motion coupled-cluster (EOM-CC) excited-state gradients and interstate nonadiabatic couplings (NACMEs) on a single 8\,GB consumer GPU. Both are built from one contraction directed acyclic graph: the EOM-CC relaxation is the reverse-mode transpose of the forward density build rather than a per-state re-derivation, and an atomic-orbital-direct Laplace-transform $J/K$ kernel, made non-symmetric ($J^x(A,B)\neq J^x(B,A)$) by the transition densities, resolves every energy denominator with no four-index molecular-orbital tensor; a two-sided Davidson returns both eigenvectors from one device-resident, spin-pure solve. The pipeline is validated end to end at small scale: gradients and NACMEs match finite differences across four spin multiplicities and full configuration interaction to $<\!10^{-12}$ for two electrons, and the excited-state gradient matches the independent Psi4 code to $\le\!4.6\times10^{-7}~E_h/a_0$ from \ce{H2O} to aromatic benzene. The kernels and the ground-state solve reach chromophores ($\le\!730$ AO) in 8\,GB, and a frozen-natural-virtual compression lets the eigensolver execute a complete excited-state gradient and $Q$–$B$ NACME of the chlorophyll-core chromophore \ce{Mg}-porphine (def2-SVP, $439$ AO) on the card. We present that run as a capability demonstration – executed and translationally invariant to machine zero, but anchored only piece-wise and bounded by a direct convergence study at ${\sim}10^{-2}~E_h/a_0$ – not a converged spectroscopic result. The validated small-scale capability and the memory-bounded implementation are the contribution.
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Quantum Physics

Spin-1 teleportation-based quantum state tomography

Gustavo Rigolin

We show that the teleportation-based quantum state tomography (QST) protocol, originally built to reconstruct qubits (spin-1/2 systems), can be extended to deal with qutrits (spin-1 systems) as well. Similarly to the original proposal, only two resources are needed to implement the spin-1 teleportation-based QST protocol: (1) Alice should be able to implement the analog of Bell measurements for spin-1 systems; and (2) she should be able to prepare a few different single qutrit states that will be teleported to Bob.
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Quantum Physics

Contractivity of the Hilbert–Schmidt Speed and Unitality–Divisibility-Based Witnesses in Finite-Dimensional Quantum Dynamics

Hossein Rangani Jahromi

We investigate the Hilbert–Schmidt speed as a witness of non-Markovianity in finite-dimensional quantum dynamics. For a differentiable one-parameter family of quantum states, the Hilbert–Schmidt speed is defined, up to a conventional factor, as the Hilbert–Schmidt norm of the corresponding Hermitian traceless tangent operator. We show that, for unital dynamics in arbitrary finite dimension, P-divisibility implies the monotonic decrease of the Hilbert–Schmidt speed. Hence, any increase in this quantity signals the breakdown of P-divisibility, and therefore also excludes CP-divisibility. For qubit systems, we establish a stronger result: every P-divisible evolution decreases the Hilbert–Schmidt speed, independently of unitality. Thus, in dimension two, HSS growth is a valid witness of non-Markovian behaviour for arbitrary positive divisible dynamics. This conclusion is dimension dependent. In dimensions $d\geq3$, non-unitality can generate HSS growth even under CP-divisible dynamics. We demonstrate this by constructing an explicit non-unital CP-divisible qutrit semigroup for which the Hilbert–Schmidt speed strictly increases. Finally, for unital GKSL dynamics, we derive a generator-level dissipation identity explaining the monotonic decay of the Hilbert–Schmidt speed. These results specify the regimes in which HSS growth can be interpreted as evidence of the failure of divisibility and clarify its limitation for higher-dimensional non-unital evolutions.
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Accelerator Physics

Using Chromaticity to Suppress Instabilities at $\gamma_t$ Transition

M. A. Balcewicz and J. Eldred

For many synchrotrons which cross $\gamma_t$ transition, a high intensity threshold has been identified beyond which significant beam losses are observed. These losses are due to a high-intensity mode coupling instability, which can be suppressed by adjusting the chromaticity curve to cross zero slightly after $\gamma_t$ transition.
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Materials Science

Domain-Growth Kinetics and Scaling Laws Governing Pulse-Driven Accumulative Polarization Switching in HZO

Manish Anand, Balram Khattar and Abhishek Sharma

Accumulative polarization switching driven by sequential sub-coercive electric-field pulses offers a promising route toward low-power ferroelectric memories and neuromorphic devices. However, the kinetic regimes governing this nonequilibrium process remain poorly understood. Here, we employ a phase-field model based on the time-dependent Landau-Ginzburg formalism to investigate pulse-driven accumulative switching in ferroelectric HZO. By systematically varying the initial domain configuration, pulse amplitude, pulse-on time, and pulse-off time, we establish a quantitative link between microscopic domain-wall dynamics and macroscopic polarization accumulation. We show that the effective switched-domain radius follows distinct scaling regimes characterized by the local kinetic exponent. Initially, a local exponent greater than 1 indicates superlinear domain growth driven by enhanced irreversible domain-wall propagation under successive pulses. As switching progresses, a local exponent close to unity marks steady self-similar growth, whereas a local exponent less than 1 signifies decelerating dynamics caused by geometric confinement, depletion of switchable polarization, and relaxation-induced back switching. The transition between these regimes is governed by the competition between field-driven excitation during the pulse-on interval and spontaneous relaxation during the pulse-off interval. The initial domain geometry further influences this transition. Increasing the pulse amplitude or pulse-on duration extends the superlinear regime, whereas longer pulse-off times promote relaxation and suppress accumulation. These findings establish a unified scaling framework for pulse-driven accumulative switching, providing quantitative insight into nonequilibrium ferroelectric domain evolution and design guidelines for HZO-based memory and neuromorphic devices.
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Materials Science

Raman spectroscopy of the van der Waals altermagnet Co$_{1/4}$NbSe$_2$

Dushyanthini Balasundaram, Bishal Thapa, Resham Babu Regmi et al. (+3 more)

We investigate the influence of Co intercalation and altermagnetic order on the lattice dynamics of the layered compound Co$_{1/4}$NbSe$_2$. Polarization-resolved Raman spectroscopy, supported by density-functional theory, enables identification of six Raman-active phonons. Co intercalation drives a substantial reconstruction of the vibrational spectrum through zone folding of NbSe$_2$ phonons, producing hybridized modes with mixed zone-center and zone-boundary character. Despite this, Co atoms do not participate in any Raman-active modes by symmetry, which is in marked contrast to related $1/3$ compounds where intercalant modes do contribute to the Raman spectrum. Temperature-dependent Raman measurements across the altermagnetic transition show no discontinuities, which is consistent with magnetic fluctuations persisting above the Néel temperature. However, we find evidence for spin-phonon coupling in $A_{1g}$ symmetry modes owing to their out-of-plane Se displacements. Our work demonstrates the substantial impact of intercalation on the vibrational properties of transition metal dichalcogenides and the presence of spin-phonon interactions in a newly discovered altermagnetic material.
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All authors Dushyanthini Balasundaram, Bishal Thapa, Resham Babu Regmi, Nirmal J. Ghimire, Igor I. Mazin, Patrick M. Vora

Quantum Physics

Entanglement Entropy of Free Fermions on Random Fractal Lattices

Arkadiusz Kosior and Jia Wang

Random fractal lattices provide a geometrically disordered setting in which quantum correlations can be shaped by noninteger dimensionality rather than onsite randomness. We investigate the entanglement properties of noninteracting fermions on random fractal lattices generated by a stochastic growth algorithm. By varying the growth parameter and adding missing links with probability $p$, we tune the Hausdorff and spectral dimensions while keeping the system free of onsite disorder. For ground states at different fillings, we compute the bipartite entanglement entropy of subregions defined by graph distance and analyze its scaling with subsystem size. Over a broad parameter range, we find robust power-law behavior governed primarily by the Hausdorff dimension, consistent with a generalized area law and without the logarithmic enhancement familiar from Euclidean free fermions. We also study entanglement growth following a global quench from an uncorrelated checkerboard state and uncover an asymptotic scaling collapse in which the subsystem-size dependence is governed by the Hausdorff dimension, while the temporal evolution is governed by the spectral dimension. The resulting dynamics are logarithmically slow over an extended intermediate-time window. These results show that geometric randomness alone can generate both nontrivial ground-state entanglement structure and slow quantum-information spreading in free-fermion systems.
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Physics and Society

Collective action through adaptive awareness

Afolabi Ariwayo, Bryce Morsky and Malbor Asllani

Collective actions emerge through the interplay between social influence and awareness. We introduce a nonlinear opinion-dynamics framework on networks in which social influence, shaped by individual interactions and community structure, promotes collective action, while awareness regulates the amount of reinforcement required for adoption. Using a degree-based mean-field reduction, we show that the competition between effective social influence and abandonment controls both the onset and persistence of collective action. Changes in awareness modify the nonlinear adoption mechanism itself, enabling populations to transition between highly responsive and weakly responsive collective states. This generates discontinuous transitions, bistability, and hysteresis, allowing collective action to persist even after the conditions that initially promoted it have weakened. We illustrate these effects through coupled disease-mitigation and resource-consumption dynamics, where external pressures act by reshaping awareness rather than social influence. More broadly, our results identify awareness as a fundamental link between environmental conditions, social interactions, and the emergence and persistence of collective action.
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High Energy Astrophysical Phenomena

Analyzing Cosmic Ray Spectral Features: A Numerical Investigation

Yuca C. Chen, Zachary M. Dorris, Eun-Suk Seo et al. (+1 more)

Recent cosmic ray space-based and balloon-borne experiments have revealed various spectral features. Spectral hardening around ~200 GV has been seen in primary nuclei as well as secondaries produced during propagation. Proton spectrum softening at ~10 TV and helium spectrum softening at a few tens TV has also been seen. Additionally, a positron excess has been observed above ~25 GeV. The cosmic ray propagation code, GALPROP v57, was utilized to investigate the cause behind these features. A diffusion model with reacceleration and convection effects was used as a baseline. To find the best fit to the experimental data, GALPROP v57's parameter optimization module, utilizing the external numerical minimization software MINUIT2, was used. For the hardening, three scenarios were studied: (1) a diffusion coefficient break, (2) injection spectra breaks, and (3) a combination of both breaks. An additional injection spectrum break was considered to fit the softening of the proton and helium spectra. An additional positron source was introduced for the positron excess. The resulting elemental spectra and ratios, along with the all-particle spectrum, are compared to compiled cosmic ray data. Implications of these spectral features are also discussed.
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All authors Yuca C. Chen, Zachary M. Dorris, Eun-Suk Seo, Vladimir S. Ptuskin

Chaotic Dynamics

Antiperiodicity in the Duffing–Holmes oscillator: symmetry origin, parity selection, and transitions

Arturo C. Marti and Edson D. Leonel

We investigate the origin and distribution of antiperiodicity — oscillations satisfying $x(t+T)=-x(t)$ — in the periodically driven Duffing–Holmes oscillator, combining analytical arguments with extensive numerical exploration. Antiperiodic orbits are precisely the periodic orbits invariant under the half-period shift symmetry $S:(x,\dot{x},t)\mapsto(-x,-\dot{x},\,t+T_d/2)$ of the equations of motion, with $T_d$ the driving period. We map the antiperiodic regions across the plane spanned by the amplitude and the frequency of the forcing, together with the periodic and chaotic domains and the potential wells visited by each orbit. The invariance under $S$ imposes a parity selection rule, verified without exception across our parameter sweeps: antiperiodic orbits lock to the drive only at odd multiples of the forcing period. Periodic orbits that lack the antisymmetry occur instead as conjugate pairs related by $S$, each orbit being the point reflection of its twin. We further show that antiperiodic orbits cannot bifurcate through a direct period doubling: the symmetry must break first, in a supercritical pitchfork in which the antiperiodic orbit splits into two conjugate, symmetry-broken orbits; alternatively, the antiperiodic orbit disappears with its symmetry intact, in a saddle-node bifurcation with an antiperiodic saddle. Antiperiodicity thus emerges as the orbit-level manifestation of a discrete symmetry of the driven system.
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Instrumentation and Methods for Astrophysics

The Wide-field Spectroscopic Telescope: optical designs for the low-resolution multi-object spectrographs

Will Saunders, Kjetil Dohlen, Dimitri Buffat et al. (+7 more)

In MOS Low-Resolution mode, WST has a 'spectral etendue' per fiber (etendue x spectral resolution elements) twice as large as any existing MOS instrument, and a total spectral etendue ~20 times larger. Combined, these present enormous challenges for the spectrograph design. Initial designs were based on (a) a novel F/0.775 Folded Solid Schmidt camera with 6cm detectors, (b) an F/1.15 dioptric camera with 6cm detectors, and (c) an F/1.31 dioptric camera with 9cm detectors, all with YAG field-flatteners. However, the imperative of fast camera speed has greatly diminished, as the projected cost and read-noise of large format CMOS detectors is projected to decrease greatly. The adopted baseline solution has 4 dioptric F/1.64 cameras, each with two doublets, a YAG field lens and 9cm x 9cm detector. Theoretical image quality is 8 microns rms radius. The design seems readily athermalised, potentially allowing passive temperature control. Each spectrograph accepts 500+ fibers. Expected RoM costs (scaled from earlier designs) suggest a total cost <4M Euro per spectrograph.
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All authors Will Saunders, Kjetil Dohlen, Dimitri Buffat, Roelof S. de Jong, Olaf Iwert, David Lee, Lawrence Bissel Andrea Bianco, Ross Zhelem, Etienne Burtin, Virgile Meyer

Earth and Planetary Astrophysics

Tracing the source of carbon oxides on the large moons of Uranus

Richard J. Cartwright, Sasha Cryan, Rosario Brunetto et al. (+15 more)

The Uranian moons Ariel, Umbriel, Titania, and Oberon are enriched in CO2 mixed with CO, but the origin(s) of these carbon oxides, be they primarily native or radiolytic, remains uncertain. Using data collected by NIRSpec on the James Webb Space Telescope (JWST), we measured the spectral signature of CO2 and other carbon oxides to help disentangle these hypotheses. Through comparison to laboratory data, we find that many of the detected spectral features are consistent with CO2 ice, including 12CO2 scattering peaks (4.15 - 4.26 microns), multi-lobe 13CO2 bands (4.35 - 4.43 microns), and CO2 biphonon and triphonon modes (4.80 - 5.25 microns). Our measurements show that CO2 and CO are concentrated on the trailing hemispheres of the inner moons Ariel and Umbriel, potentially supporting a radiolytic production hypothesis, consistent with prior ground-based results. However, many of the identified spectral features are only observed in thick crystalline ice deposits measured in the laboratory, which may be difficult to form via radiolysis of carbon-bearing material mixed in icy regoliths. Similarly, the data exhibit weak 4.02 microns and 4.40 microns bands, hinting at the presence of carbonate minerals and 13CO2 clathrates, respectively, possibly formed in the interiors of these moons. Furthermore, JWST has revealed that CO2 is widespread at Uranus, present in its system of rings, ring moons, and irregular satellites, consistent with its largest moons accreting CO2 and other carbon oxides from the Uranian subnebula. We conclude that exposed carbon oxides are potentially native, with their surface distributions shaped by charged particle irradiation and seasonal sublimation-condensation cycles.
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All authors Richard J. Cartwright, Sasha Cryan, Rosario Brunetto, Apolline Leclef, Eric Quirico, Bryan J. Holler, William M. Grundy, Tom A. Nordheim, Ujjwal Raut, Matthew M. Hedman, Riley A. DeColibus, Chloe B. Beddingfield, Marc Neveu, Christopher R. Glein, Sara Faggi, Geronimo L. Villanueva, Noemi Pinilla-Alonso, Stephanie M. Menten

Nuclear Experiment

$K^{*}(892)^0$ production and the time between freeze-outs in $^{40}$Ar+$^{45}$Sc collisions by NA61/SHINE at the CERN SPS

NA61/SHINE Collaboration: P. Adrich, K.K. Allison, M. Bajda et al. (+108 more)

The analysis of the production of strange $K^{*}(892)^0$ resonances allows us to better understand the temporal evolution of high-energy nucleus–nucleus collisions. In particular, the ratio of $K^{*}(892)^0$ to charged kaon yields is used to determine the time interval between chemical and kinetic freeze-outs. In this paper, the first measurements of $K^{*}(892)^0$ production in central $^{40}$Ar+$^{45}$Sc collisions at the CERN Super Proton Synchrotron are reported. They were performed by NA61/SHINE at collision center-of-mass energies per nucleon pair $\sqrt{s_\mathrm{NN}}$ = 8.8, 11.9, 16.8 GeV. The obtained $\langle K^{*}(892)^0 \rangle/\langle K^{+} \rangle $ and $\langle K^{*}(892)^0 \rangle/\langle K^{-} \rangle$ mean multiplicity ratios are compared with corresponding results in $p$+$p$ collisions, allowing for an estimate of the time interval between chemical and thermal freeze-outs in the $^{40}$Ar+$^{45}$Sc system. These are the first such results reported for $^{40}$Ar+$^{45}$Sc collisions.
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All authors NA61/SHINE Collaboration: P. Adrich, K.K. Allison, M. Bajda, Y. Balkova, D. Battaglia, M. Bielewicz, A. Blondel, M. Bogomilov, Y. Bondar, J. Brzychczyk, M. Buryakov, A.F. Camino, Y.D. Chandak, M. Csanád, M. Ćwiok, T. Czopowicz, C. Dalmazzone, N. Davis, A. Dmitriev, P. von Doetinchem, W. Dominik, J. Dumarchez, R. Engel, L. Fields, Z. Fodor, M. Friend, M. Gaździcki, K.E. Gollwitzer, V. Golovatyuk, K. Grebieszkow, P.G. Hurh, S. Ilieva, V.A. Kireyeu, R. Kolesnikov, D. Kolev, Y. Koshio, S. Kowalski, T. Kowalski, B. Kozłowski, A. Krasnoperov, W. Kucewicz, M. Kuchowicz, P. Lasko, A. László, M. Lewicki, G. Lykasov, J.R. Lyon, V.V. Lyubushkin, M. Maćkowiak-Pawłowska, B. Maksiak, A.I. Malakhov, A. Marcinek, A.D. Marino, T. Matulewicz, V. Matveev, G.L. Melkumov, Ł. Mik, Y. Nagai, R. Nagy, T. Nakadaira, S. Nishimori, A. Olivier, V. Ozvenchuk, O. Panova, V. Paolone, I. Pidhurskyi, R. Płaneta, B.A. Popov, B. Pórfy, D. Pszczel, S. Puławski, L. Ren, V.Z. Reyna Ortiz, D. Röhrich, M. Roth, Ł. Rozpłochowski, M. Rumyantsev, A. Rustamov, M. Rybczyński, A. Rybicki, D. Rybka, K. Sakashita, K. Schmidt, P. Semeniuk, H. Shah, U.A. Shah, Y. Shiraishi, A. Shukla, M. Słodkowski, P. Staszel, G. Stefanek, J. Stepaniak, T. Šuša, Ł. Świderski, J. Szewiński, R. Szukiewicz, A. Tefelska, D. Tefelski, V. Tereshchenko, R. Tsenov, L. Turko, M. Unger, M. Urbaniak, D. Veberič, O. Vitiuk, A. Wickremasinghe, K. Witek, K. Wójcik, A. Zaitsev, E. Zherebtsova, E.D. Zimmerman

Quantum Physics

Wilczek-Zee Realization of Uhlmann Parallel Transport

Yu-Huan Huang, Xu-Yang Hou, Jia-Chen Tang et al. (+1 more)

The Uhlmann phase extends geometric phases to mixed quantum states via a parallel-transport condition on purification amplitudes, yet its direct implementation under standard Hamiltonian dynamics is obstructed by the non-Hermitian nature of the purification. We establish that for any smooth one-dimensional closed loop of full-rank qubit density matrices, there exists a four-level Hermitian parent Hamiltonian whose doubly degenerate ground-state subspace carries a Wilczek–Zee connection exactly equal to the Uhlmann connection. Consequently, the Uhlmann holonomy is faithfully reproduced by adiabatic evolution in the enlarged system. We further prove that this auxiliary-field construction is obstructed in generic two-dimensional parameter spaces by a Frobenius integrability condition, which we derive explicitly. The one-dimensional Uhlmann phase is thus placed on the same footing as the non-Abelian Berry phase, offering a purely Hermitian, Hamiltonian-based route to simulating mixed-state geometric phases. Numerical integration of the adiabatic dynamics confirms the exact correspondence and validates the convergence to the Uhlmann holonomy in the large-gap limit.
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All authors Yu-Huan Huang, Xu-Yang Hou, Jia-Chen Tang, Hao Guo

High Energy Physics (Theory)

M-theory geometries from five-brane webs, seven-branes, and T-branes

Andrés Collinucci

We track the chain of dualities relating five-brane webs in Type IIB to M-theory on noncompact Calabi-Yau threefolds, and follow the effect of adding $(p,q)$ seven-branes. T-dualizing along the seven-brane, a junction of D5-branes ending on a D7-brane becomes a single smooth D6-brane wrapping a smooth holomorphic curve, which uplifts directly to an M-theory geometry. Treating the branes as coherent sheaves (tachyon condensation), we obtain a spectral-curve dictionary that maps non-Abelian (T-brane) partition data to explicit complex-structure deformations of the threefold. As applications we (i) give a physical derivation of these deformations, (ii) exhibit a simple geometric prototype of an s-rule violation, and (iii) link T-brane data to geometry.
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Physics and Society

Three Centuries of the Laws of Cricket Reveal Core Principles of the Evolution of Regulatory Mechanisms

Daniel Chia, Hyejin Youn, Jonny Singer et al. (+5 more)

Rules, regulations, and regulatory systems are central to societies, institutions, and organisms, yet surprisingly little is known about their evolution over long timescales. The Laws of Cricket, the world's second most popular sport, offer a unique insight into this fundamental question. Their 268-year history constitutes the longest continuous rule-set record yet assembled. Our quantitative analysis reveals generic features including rule-book size growing exponentially in time but scaling sublinearly with matches played; new situations stimulate new rules, but at a decelerating rate; regulatory structures exhibit abrupt phase transitions, increasing rule specificity, interconnectivity and complexity with central rules shifting from gameplay to officiating. These provide a framework for understanding how governance evolves from simple collections of rules to complex regulatory architectures across social, legal, and biological domains.
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All authors Daniel Chia, Hyejin Youn, Jonny Singer, Dawoon Jeong, Chris Kempes, C. Brandon Ogbunugafor, Geoffrey B. West, James Holehouse

Quantum Physics

Nonlocal transfer of quantized toroidal magnetic flux

Adel Ali and Alexey Belyanin

We propose a nonlocal flux-transfer experiment in which a quantized magnetic-field excitation confined within one toroidal superconducting structure is coherently transferred to a spatially separated toroid without magnetic-field occupation of the intervening region. The transfer arises from quantized Aharonov-Bohm-type vector potential coupling mediated by a superconducting loop threading the toroids, which, however, remains in the ground state, acting only through a global fluxoid constraint. A direct experimental signature would be the observation of correlated, time-resolved flux exchange between remote toroids in a SQUID readout. We analyze an apparent signaling paradox related to this interaction as a probe of the broader question of whether spatiotemporal quantum coherence is fundamentally bounded. The proposed setup can provide an experimental testbed for addressing foundational questions such as the existence of an objective collapse of a wavefunction or the fundamental limits of macroscopic quantum coherence which is relevant to large scale quantum computers.
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Quantum Physics

Reduced Quantum-Reference-Frame Channels for Open Quantum Systems

Paolo Luppi, Viktoria Kabel, Flaminia Giacomini et al. (+1 more)

When reference frames are treated quantum mechanically, the subsystem structure of quantum systems is no longer absolute, but depends on the choice of the quantum reference frame (QRF). This raises a basic question: which dynamical properties are preserved across QRFs, and which depend on the physical reference used to define the system? We study this question in the general setting of open quantum systems. At the operational level, after a QRF transformation, the old reference frame and environmental degrees of freedom may be inaccessible and must therefore be traced out. This motivates the definition of reduced quantum-reference-frame channels: maps that connect the joint description in one frame to the accessible subsystem in another. We characterize their symmetry-constrained structure and define a regime in which a reduced entropy-coherence conservation law holds. We also identify when the induced reduced action on the open system admits a classical interpretation as random frame misalignment, and when it instead reflects quantum reduced-frame effects. We then apply the framework to pure-dephasing dynamics and derive a necessary and sufficient compatibility condition for population preservation. When the frame symmetry commutes with the open system's free Hamiltonian, coherences acquire a multiplicative frame factor, so that locally inferred decoherence rates split into environmental and reference-induced contributions. Ramsey interferometry gives this split a direct operational meaning. Finally, a gravity-motivated dephasing model illustrates how degradation of a phase reference can mimic signatures usually attributed to intrinsic decoherence mechanisms.
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All authors Paolo Luppi, Viktoria Kabel, Flaminia Giacomini, Andrea Smirne

High Energy Physics (Phenomenology)

Linear Breit-Wheeler pair production in the search for axion-like particles

Thomas Rook, Wei Wu, Stuart P. D. Mangles et al. (+1 more)

Assuming the existence of axion-like particles (ALPs), the standard Quantum Electrodynamics (QED) amplitudes for the linear Breit-Wheeler (BW) pair production process are shown to be supplemented by an additional ALP-mediated amplitude. We compute the coherently combined cross section and show that, for pseudoscalar ALPs, interference with QED produces an asymmetric Fano-type resonance. We propose experimental observation of the BW process with real photons as a complementary probe of MeV-scale ALPs, coupling jointly with photons and electron-positron pairs, on the basis that it occupies a kinematic region not readily accessible to other ALP search methods.
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All authors Thomas Rook, Wei Wu, Stuart P. D. Mangles, Steven J. Rose

Earth and Planetary Astrophysics

Dynamical constraints on planet engulfment as the origin of lithium enhancement in TOI-5882

C. Charalambous, C. Aguilera-Gómez, S. Urrutia et al. (+1 more)

As stars evolve off the main sequence, changes in stellar structure can alter the dynamical architecture of planetary systems and, in some cases, lead to planet engulfment events capable of producing observable chemical signatures such as lithium enhancement. TOI-5882 is a lithium-rich subgiant hosting a 22 m_Jup brown dwarf on a 7.1-day orbit, where the enrichment could plausibly result from the recent engulfment of a super-Earth to Neptune-mass planet. We assess the dynamical viability of a planet engulfment scenario in the TOI-5882 system that could explain its observed Li enrichment. We combine stellar evolution models with N-body simulations that incorporate time-dependent stellar properties as the host star leaves the main sequence, exploring a broad range of pre-engulfment planetary masses and orbital configurations. Planet engulfment is the most probable outcome under the explored configurations. However, only 5% of the simulations produce engulfment within the short detectability window of the lithium-enrichment signature. Engulfment therefore remains a viable explanation for the observed Li enhancement in TOI-5882, but only for a relatively uncommon subset of the initial conditions considered here. Under our simplified architecture, recent engulfment cannot be ruled out as the origin of the observed lithium enhancement. However, because successful cases represent only a small fraction of the initial conditions explored here, and because additional processes such as wind-induced drag forces were not included, additional constraints on the system's primordial architecture are needed to assess how likely this scenario is for TOI-5882.
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All authors C. Charalambous, C. Aguilera-Gómez, S. Urrutia, C. Norambuena

Applied Physics

Structured Illumination Scanning Thermography (SISTER)

Pengfei Zhu, Julien Lecompagnon, Philipp Daniel Hirsch et al. (+1 more)

Conventional non-invasive photothermal imaging techniques are fundamentally constrained by the diffusive nature of heat transport, which causes severe energy dissipation during subsurface reconstruction. Although modulation-based approaches partially mitigate this limitation by encoding depth information into phase delay and amplitude attenuation, they remain inherently restricted by repeated temporal excitation, long acquisition times, and stitching artifacts in large-area inspection. In this work, we propose a structured illumination scanning thermography (SISTER) framework that replaces conventional temporal modulation with continuous spatial scanning under static structured illumination. The key theoretical insight is that heat diffusion is governed by a Markov semigroup, while sample motion transforms static spatial illumination into an equivalent temporal excitation through a Galilean coordinate transformation. This formulation enables dynamic-to-static reconstruction without repeated temporal modulation and provides a unified interpretation of spatial scanning and conventional signal modulation. A scanning system is integrated to implement the proposed framework together with a dynamic-to-static reconstruction algorithm for continuous subsurface defect inspection. Both numerical simulations and experimental results demonstrate that the proposed method significantly improves spatial continuity, signal-to-noise ratio, and detection capability while effectively eliminating stitching artifacts and reducing acquisition complexity. The proposed SISTER framework establishes a unified theoretical foundation for scanning photothermal imaging and provides a practical paradigm for high-efficiency, large-scale industrial non-destructive testing.
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All authors Pengfei Zhu, Julien Lecompagnon, Philipp Daniel Hirsch, Mathias Ziegler

Optics

Quantitative Benchmarking of Spectroscopic Homogeneous and Inhomogeneous Linewidth Separation

Adam Alfrey, Cole Tait, Joshua R. Hendrickson et al. (+1 more)

Separating homogeneous and inhomogeneous contributions to a spectral linewidth is essential for connecting optical spectra to microscopic dephasing and disorder. We quantitatively compare linewidth separation by one-dimensional Voigt analysis and two-dimensional coherent spectroscopy (2DCS). Using photoluminescence and 2DCS measurements of the same hBN-encapsulated monolayer MoSe2 sample, we construct uncertainty-weighted ḩi}^2 landscapes for the Gaussian inhomogeneous width and Lorentzian homogeneous half-width. Although a Voigt profile accurately reproduces the photoluminescence spectrum, the two widths are strongly anticorrelated and therefore poorly determined independently. By contrast, joint fitting of diagonal and cross-diagonal 2DCS slices produces more compact confidence regions with reduced parameter correlation and elongation. These results quantitatively demonstrate the improved linewidth separation provided by 2DCS and illustrate the limitations of assigning homogeneous and inhomogeneous contributions from one-dimensional Voigt fits alone.
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All authors Adam Alfrey, Cole Tait, Joshua R. Hendrickson, Steven T. Cundiff

Materials Science · Cross-listed from cs.LG

EquiFiLM: Charge-Conditioned Equivariant Force Fields via Feature-wise Linear Modulation

Samuel Sahel-Schackis, Ken-ichi Nomura, Aiichiro Nakano et al. (+2 more)

Foundation machine learning force fields (MLFFs) such as MACE-MP-0 and UMA cover broad chemical space at near density functional theory (DFT) accuracy. However, they assume equilibrium ground-state physics and do not natively handle externally induced changes to the electronic state, such as charging, applied fields, or electronic excitation, which limits their use for driven processes such as photoexcitation and charge injection. We propose EquiFiLM, a lightweight extension that adds continuous external conditioning to any equivariant foundation MLFF via a per-layer Feature-wise Linear Modulation (FiLM) block, learning externally driven changes to the potential energy surface from minimal training data. The block modulates only scalar channels and preserves E(3)-equivariance exactly. We demonstrate the recipe on charged liquid water with the foundation model MACE-MatPES as the backbone, yielding E-MACE. On the four training charges, E-MACE delivers a $3.1\times$ reduction in force RMSE ($21.3$ to $6.96$ meV/$\mathring{A}$) and a $61\times$ reduction in per-atom energy RMSE ($6.1$ to $0.1$ meV/atom) over a baseline without EquiFiLM trained on the same data, at indistinguishable inference cost. Across seven held-out interpolation and extrapolation charges, force RMSE stays within $18-61$ meV/$\mathring{A}$ and energy RMSE within $0.7-5.4$ meV/atom. The model runs stable molecular dynamics across the full range tested and predicts the charge-dependent first-shell response of the reduced pair distribution function probed by ultrafast electron diffraction. Adding this conditioning axis to the foundation requires only a few thousand DFT-labeled frames, against the $\approx 10^8$ structures of a charge-aware foundation trained from scratch. The recipe is backbone- and conditioning-agnostic: it applies without architectural change to any equivariant MLFF with scalar interaction-layer channels.
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All authors Samuel Sahel-Schackis, Ken-ichi Nomura, Aiichiro Nakano, Matthias F. Kling, Thomas Linker

Nuclear Theory

Can average speed of sound and thermodynamic response functions signal the exotic phases in neutron star cores?

Suman Pal and Gargi Chaudhuri

The speed of sound in dense nuclear matter is crucial for understanding neutron star structure and constraining the EOS. We have discussed in details the decomposition of speed of sound via the average speed of sound and its logarithmic derivative and have connected it to the other two decomposition schemes via slope and curvature of the energy per particle or through the normalized trace anomaly and its derivative. These thermodynamic variables provide important diagnostic tools for the composition of the inner core of the compact stars. We discuss a new method of understanding phase transition and the microphysics of dense matter through the thermodynamic response functions like isothermal compressibility, baryon number susceptibility and bulk modulus in order to distinguish between local (sharp interface) and global charge (mixed phase) neutrality conditions, thereby revealing the signatures of the phase transition. The corresponding neutron-star mass–radius relations demonstrate that all considered equations of state satisfy current astrophysical constraints, while the most massive stable configurations contain either an extended mixed phase or a quark core depending on the phase-transition construction.
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High Energy Physics (Theory)

Domain Walls in Large-$N$ QCD$_3$

Adi Armoni and Jonathan Whittle

Large-$N$ three dimensional QCD with a level $k$ Chern-Simons term and $N_f$ massless flavours admits $N_f+1$ degenerate vacua. We discuss various aspects of the domain walls that interpolate between those vacua. Using a bosonic dual for the case $k \ge N_f/2$ we write down the profile of the composite wall. By fluctuating the profile, we find the 2d field theory that lives on the wall, a level-$N$ gauged WZW model, and compare it with a theory that was previously obtained by using anomaly inflow considerations. We also discuss the case $k < N_f/2$. Finally, we remark on the realisation of the wall as a D-brane in a holographic dual.
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General Relativity and Quantum Cosmology

Charged black holes embedded in matter with anisotropic pressure: Horizon Structure and Quasinormal Mode Spectra

D. N. Garzon, Jiayi Zhang, Elena Kopteva et al. (+1 more)

In realistic settings, black holes are expected to be embedded in astrophysical environments. These environments, including possible dark matter distributions, can modify observable properties of black holes and leave imprints on their quasinormal mode spectra. In this work, we model the environment as matter with anisotropic pressure, and we consider a charged black hole embedded in it. The resulting spacetime is described by the Kiselev metric. We first analyze its horizon structure. We then investigate the quasinormal modes of a massless charged scalar field propagating on this background. For this purpose, we develop a nontrivial extension of Leaver's continued fraction method to incorporate the effects of the surrounding matter, and we combine this framework with automatic differentiation techniques. We also compare our results to those obtained with the sixth-order Wentzel-Kramers-Brillouin approximation. We find that the surrounding matter modifies the oscillation frequencies and damping rates and leads to the appearance of long-lived modes. We also identify avoided crossings regions and reorganization of the modes in the spectra. Our results demonstrate the importance of incorporating surrounding matter when modeling realistic black holes. The numerical framework we developed here provides a tool for studying quasinormal modes in non-vacuum spacetimes and can be extended to a broad class of black-hole geometries embedded in matter fields.
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All authors D. N. Garzon, Jiayi Zhang, Elena Kopteva, Helvi Witek

Mesoscale and Nanoscale Physics

Effect of pressure on the magnetic properties of (Co$_{0.5}$Fe$_{0.5}$)$_5$GeTe$_2$

Tamás Prok, Zoltán Kovács-Krausz, Harvey Stanfield et al. (+9 more)

Cobalt-doped Fe$_5$GeTe$_2$ possesses a rich magnetic phase diagram as a function of Co concentration. The nature of magnetic order in (Co$_{0.5}$Fe$_{0.5}$)$_5$GeTe$_2$ is especially interesting, as it has been shown to exhibit ferromagnetic order, A-type antiferromagnetic (AFM) order, or potentially both at the same time. Here we present magnetoresistance measurements on antiferromagnetic (Co$_{0.5}$Fe$_{0.5}$)$_5$GeTe$_2$ at a series of pressures and extract the anisotropy and interlayer exchange fields using the two-sublattice model. We show a 50 % increase of the interlayer exchange at 2 GPa, highlighting the sensitivity of magnetic properties to interlayer distance. In addition, we find that the sharp hysteretic transitions observed within the AFM state can be qualitatively described by a linear chain model, which suggests an even-odd effect as a function of layer number instead of a coexisting ferromagnetic phase.
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All authors Tamás Prok, Zoltán Kovács-Krausz, Harvey Stanfield, Bing Zhao, Michael Leonárd Morgan, Bálint Fülöp, Marcos H. D. Guimarães, Ivan J. Vera-Marun, Saroj Prasad Dash, Szabolcs Csonka, Péter Makk, Endre Tóvári

Mesoscale and Nanoscale Physics

Magnetotransport of tomographic electrons in a Corbino disk

Nitay Ben-Shachar and Johannes Hofmann

In clean electron gases at low-to-moderate temperatures, odd-parity modes of the Fermi surface are anomalously long-lived due to Pauli blocking, giving rise to “tomographic transport” that is not captured by a hydrodynamic model. Here we show that tomographic flow in a Corbino disk induces an extended boundary layer near electrodes with superballistic transport and enhanced slip velocity, which leads to a parametric enhancement of the quadratic magnetoresistance coefficient. The enhancement depends explicitly on the electrode curvature, allowing its strength to be controlled by the device geometry. The magnetoresistance coefficient reveals three distinct regimes as a function of magnetic field: a tomographic regime at weak fields; a hydrodynamic regime at intermediate fields, reached when the cyclotron radius becomes comparable to a large odd-mode mean free path; and a conventional Ohmic regime at large fields, reached when the cyclotron radius becomes comparable to the short even-mode mean free path. The tomographic regime is characterized by an anomalous dependence of the magnetoresistance on temperature and density, which may account for recent experimentally observed anomalous scaling of the electron viscosity.
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High Energy Physics (Theory)

Localized zero modes enhance massive Casimir interactions

Jose M. Muñoz-Castañeda, Inés Cavero-Peláez and Gonzalo Sancho-Garrido

Massive quantum fields ordinarily produce strongly screened Casimir interactions at large separation. We show that a normalisable localised zero mode can change this asymptotic behaviour: it opens an additional interaction channel whose decay is parametrically slower than that due to the exchange of massive quantum fluctuations, even though the continuum itself remains gapped. We demonstrate this mechanism analytically and show that the massive quantum fluctuations provide the local dressing of each object's coupling to the zero-mode fluctuations. The sine-Gordon kink provides an exactly solvable realisation in which the Casimir interaction exhibits the predicted zero-mode-dominated large-distance behaviour, with the enhancement localised around the kink.
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High Energy Physics (Theory)

Ten-dimensional localization

Christopher Couzens, Alice Lüscher and James Sparks

We construct equivariantly closed polyforms for the fluxes and the action of (massive) type IIA and type IIB supergravity directly in ten dimensions. We illustrate applications of our formalism to two distinct classes of solutions in massive type IIA. Our analysis straightforwardly reproduces and vastly generalizes all known results for on-shell actions in these classes, with no need for a consistent truncation. Where known, we match the corresponding field theory partition functions at leading order, and our results extend easily to other solutions of type II supergravity.
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